1. Field of the Invention
The present invention relates to a radio base station receiver that conducts reception of communication data from a plurality of users, and particularly to a method of managing process resources for processing received data of an uplink transmission (data transmitted from mobile terminals to the radio base station) in the radio base station receiver.
2. Description of the Related Art
Recently, a 3rd generation service started in mobile radio systems, and a CDMA (Code Division Multiple Access) method is used in the mobile radio systems of the 3rd generation. The mobile radio system of the CDMA method such as the above is disclosed in Patent Document 1 below.
FIG. 1 shows an example of a basic configuration of a radio base station receiver in a mobile radio system using the CDMA method. In the receiver shown in FIG. 1, received data of an uplink transmission is converted from data in a radio frequency band into digital data in a baseband frequency band by an RF (Radio Frequency) processing circuit 70 and an A/D (Analog/Digital) converter circuit 80 after being received by an antenna 60. A despreading process is executed by a despreading process unit 30 on the received data of the uplink transmission that has been converted into the digital data. Because the data demodulated through the despreading process was subjected to an encoding process (Viterbi encoding, Turbo encoding, or the like) by a channel coding process when being transmitted, a decoding process is executed on the demodulated data by a channel decoding process unit 40 in order to convert the data back into its original state. In the receiver, the number of resources for executing processes is limited depending on the processing capacity of the device; accordingly, the entire process amount is controlled by resource management unit 10 managing the resources.
FIG. 2 shows the despreading process unit 30, the channel decoding process unit 40, and resource management unit 10 for managing the resources of the despreading process unit 30 and channel decoding process unit 40 in a conventional example. In the conventional example, in order to simultaneously conduct reception of uplink data from a plurality of users, the resources for the despreading process by the despreading process unit 30 and the resources for the channel decoding process by the channel decoding process unit 40 are prepared such that they are of the same number, and the above resource management unit 10 conducts allocation such that the ratio of the resource for the despreading process to that for the channel decoding process is 1:1.
Next, a process flow of the above resource management unit 10 is explained by referring to FIG. 3.
Resource management unit 10 is activated by a resource allocation request from a higher layer, and checks the number of remaining resources in step S50. When the resource allocation cannot be conducted because there is no available resource, the process proceeds to step S53, and an NG response indicating that the allocation cannot be conducted is made to the higher layer in order to report resource depletion. When there are available resources, the resources are allocated to the despreading process unit 30 and the channel decoding process unit 40, the number of remaining resources is decremented by one in step S51, and a completion response of the resource allocation is made to the higher layer in step S52.
As mobile radio systems such as the above have realized higher speed and a broader band, not only conventional voice communications, but also various services utilizing packet communications have been realized. Accordingly, the percentage of communication data used in the packet data communication services to the uplink data received by the radio base station has increased.
Additionally, competition among network operators has become more intensive, and the infrastructures of the base stations and the like are increasingly required to be of a lower cost.
Patent Document 1
Japanese Patent Application Publication No. 2005-136986
Voice communication such as telephone calls or the like are included in types of continuous communications because the data to be received is continuously transmitted. In contrast, in communications such as packet data communications or the like, the data to be received does not arrive continuously.
In radio base station devices, in order to secure radio links between the base station device and terminal devices (in order to secure pilot synchronization), the despreading process has to be continuously executed for demodulating pilot signals even in communication services other than continuous communication services, such as packet data communication. However, when there is no user communication data to be transmitted, the channel decoding process unit does not have to operate.
In the conventional examples, as many resources for the channel decoding processes as there are resources for the despreading processes are required because the resources for the despreading processes and the resources for the channel decoding processes are managed such that the ratio therebetween is 1:1. Thus, even when a data process is not executed, the resources for the channel decoding processes for the maximum number of users to whom the service can be provided simultaneously are secured.
However, for packet communication, it is sufficient that the channel decoding process unit is used only when data is processed; accordingly, it is not necessary to occupy the resources for the channel decoding processes continuously.
In the conventional examples, in a device that conducts reception of data from a plurality of users such as the radio base station receiver, both of the resources for the despreading processes and the resources for the channel decoding processes are prepared such that they are of the same number as the users whose data is processed simultaneously. Accordingly, a problem is created in which the circuit scale of the radio base station receiver becomes large.
It is an object of the present invention to prevent the circuit scale of the radio base station receiver from becoming large, and to reduce the cost of the radio base station device.